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As far as I know Sulfuric acid decompose slowly to SO3 and water at temperatures above 340C.
I am looking for data on the decomposition rate and equilibrium composition/partial pressure of a close system containing (before heating) sulfuric acid and water in the range of 50% weight and at temperatures up to 600C.
Will the sulfuric acid completely decompose?
Would there be a clear distinction between a liquid phase of sulfuric acid+water and a gas phase above it, containing water, sulfuric acid and SO3?